Ice‐volcano interactions during the 2010 Eyjafjallajökull eruption, as revealed by airborne imaging radar

Abstract

[1] During the eruption of the ice-covered Eyjafjallajökull volcano, a series of images from an airborne Synthetic Aperture Radar (SAR) were obtained by the Icelandic Coast Guard. Cloud obscured the summit from view during the first three days of the eruption, making the weather-independent SAR a valuable monitoring resource. Radar images revealed the development of ice cauldrons in a 200 m thick ice cover within the summit caldera, as well as the formation of cauldrons to the immediate south of the caldera. Additionally, radar images were used to document the subglacial and supraglacial passage of floodwater to the north and south of the eruption site. The eruption breached the ice surface about four hours after its onset at about 01:30 UTC on 14 April 2010. The first SAR images, obtained between 08:55 and 10:42 UTC, show signs of limited supraglacial drainage from the eruption site. Floodwater began to drain from the ice cap almost 5.5 h after the beginning of the eruption, implying storage of meltwater at the eruption site due to initially constricted subglacial drainage from the caldera. Heat transfer rates from magma to ice during early stages of cauldron formation were about 1 MW m À2 in the radial direction and about 4 MW m À2 vertically. Meltwater release was characterized by accumulation and drainage with most of the volcanic material in the ice cauldrons being drained in hyperconcentrated floods. After the third day of the eruption, meltwater generation at the eruption site diminished due to an insulating lag of tephra.

The role of multiple glacier outburst floods in proglacial landscape evolution: The 2010 Eyjafjallajokull eruption, Iceland

“…While the 14 April fl ood took 36 min to peak at 2640 m 3 s −1 at OMB, the 15 April event took only 14 min, with a recorded peak discharge of 1400 m 3 s −1 ; this compares to normal base fl ow of 42.6 m 3 s −1 at OMB (Snorrason et al, 2012). These discharge estimates are likely to be highly attenuated; the 15 April jökulhlaup was estimated by Magnússon et al (2012) to have peaked between 5000 and 15,000 m 3 s −1 . Gígjökulslón was completely infi lled with sediment and ice blocks by the end of 15 April 2010.…”

“…The eruption within the summit caldera of Eyjafjallajökull began on 14 April 2010, melting ~0.08 km 3 of ice during the fi rst week to create a series of jökulhlaups (Magnússon et al, 2012). The eruption-generated jökulhlaup sequence was dominated by 2 large outburst fl oods totaling 57…”

“…On 14 April, after an initial period of storage in the fi rst of several melt cauldrons, meltwater drained subglacially and supraglacially (Magnússon et al, 2012). The fl uidal turbulent jökulhlaup entered Gígjökulslón, the ~0.6 km 2 , 20-30-m-deep proglacial lake at the terminus of Gígjökull glacier (Magnússon et al, 2012;Fig. 2A).…”

“…This had a high tephra:water ratio and was observed as a supraglacial slurry fl ow that entrained ice and surface snow (Magnússon et al, 2012), passing a stage recorder at the old Markarfl jót Bridge (OMB, Fig. 1) as a hyperconcentrated fl ow.…”

Pyroclastic passage zones in glaciovolcanic sequences

“…Although the transport capability of melt water within this layer is very low 40 , it allows the possibility of stored englacial lake waters draining through the upper portion of the glacier 16,42,43 . Depths to the firn-ice transition vary somewhat (15- 115 m (ref.…”